The long term objective of this research is to develop x-ray systems that will minimize x-ray radiation dose to the patient during clinical diagnosis and routine screening while maximizing the usefulness of data by applying advanced sensing and signal processing techniques. Near theoretical limit x-ray sensitivity can be achieved with advanced semiconductor detector arrays so that x-ray radiation dose can be reduced by more than an order of magnitude from that required by conventional screen-film systems. the inherently digital output of the detector array is ideally suited for Computed Radiology including: electronic archiving and image transmission, image enhancement and analysis, and computer aided diagnosis. Specific aims during Phase I are: to produce a preliminary digital mammography system design to determine performance requirements for each of the subsystems; to design, fabricate, and test the critical detector arrays; to address the key detector packaging and system mechanical design issues; and to design the data acquisition subsystem and produce a detailed image display, enhancement, analysis, and archiving software plan.